用超细笔形束X射线源进行X射线荧光计算机断层成像（XFCT）
X-ray fluorescence computed tomography (XFCT) imaging with a superfine pencil beam x-ray source
摘要：
X射线荧光计算机断层成像（XFCT）是一种X射线光子的分子成像技术，其可用于感测深层样品或组织内的不同元素或纳米颗粒（NP）剂。XFCT多年来一直是一个活跃的研究课题。然而，XFCT尚未成为流行的分子成像工具，因为它具有有限的分子灵敏度和空间分辨率。为了进一步研究XFCT成像，我们提出了一个台式XFCT成像系统，其中一个独特的笔形束X射线源和一个环的X射线光谱仪使用GATE（Geant 4应用断层扫描发射）软件进行了模拟。采用一种基于L1正则化的优化最小化算法（MM），从GATE模拟的数值测量数据中重建了钼（Mo）NP靶的X射线荧光图像。在较低的X射线源输出率下，实现了良好的靶定位，DICE系数为83.681%。重建的信号强度的目标被发现是相对成比例的目标浓度，如果检测器的数量和位置进行了优化。将MM算法的性能与极大似然期望最大化（ML-EM）和滤波反投影（FBP）算法进行了比较。未来将对台式XFCT成像系统进行实验测试
英文摘要：
X-ray fluorescence computed tomography (XFCT) is a molecular imaging technique of x-ray photons, which can be used to sense different elements or nanoparticle (NP) agents inside deep samples or tissues. XFCT has been an active research topic for many years. However, XFCT has not been a popular molecular imaging tool because it has limited molecular sensitivity and spatial resolution. To further investigate XFCT imaging, we present a benchtop XFCT imaging system, in in which a unique pencil beam x-ray source and a ring of x-ray spectrometers were simulated using GATE (Geant4 Application for Tomographic Emission) software. An accelerated majorization minimization (MM) algorithm with an L1 regularization scheme was used to reconstruct the XRF image of Molybdenum (Mo) NP targets from the numerical measurements of GATE simulations. With a low x-ray source output rate, good target localization was achieved with a DICE coefficient of 83.681%. The reconstructed signal intensity of the targets was found to be relatively proportional to the target concentrations if detector number and placement is optimized. The MM algorithm performance was compared with maximum likelihood expectation maximization (ML-EM) and filtered back projection (FBP) algorithms. In the future, the benchtop XFCT imaging system will be tested experimentally
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